1) Field of the Invention
The present invention relates to an elastic synthetic polymer filament with a multi-lobated cross-sectional profile and comprising a thermoplastic elastomer. More particularly, the present invention relates to an elastic synthetic polymer filament with a multi-lobated cross-sectional profile, comprising a thermo-plastic elastomer and having an enhanced resistance to breakage by a sewing needle and a high resistance to photo-deterioration and chlorine-deterioration.
2) Description of the Related Arts
It is known that various thermoplastic elastomers, for example, polyurethane resins and polyetherester block copolymer resins, are utilized for forming elastic filaments. These conventional elastic filaments are advantageous in having a high elastic recovery but are disadvantaged by a poor resistance to photo-deterioration and chlorine-deterioration.
Various attempts have been made to eliminate the above-mentioned disadvantages; for example, Japanese Examined Patent Publication No. 52-22,744 and Japanese Unexamined Patent Publication No. 62-192,450 disclose that the conventional thermoplastic elastomer is mixed with a protective additive consisting of an ultraviolet ray-absorbant or antioxidant, for example, a hindered phenol compound, a benzotriazol compound, a salicylic acid ester compound or titanium dioxide. These attempts, however, have not provided a satisfactory improvement, and thus are not practically utilized for the following reasons.
When the conventional elastic filaments are used in the form of a multifilament yarn, the resultant elastic multifilament material, for example, swim wear, exhibits a poor resistance to ultraviolet ray-deterioration and an unsatisfactory resistance to chlorine-deterioration. In the multifilament yarn materials, it is known that the smaller the denier of the individual filaments, the poorer the resistance to the above-mentioned deterioration (lowering of the mechanical strength). Therefore, the use of the conventional elastic multifilament yarn materials is strictly restricted to a specific scope.
When the conventional elastic filaments are used in the form of a monofilament yarn, the resultant elastic monofilament yarn materials have a higher resistance to the above-mentioned deterioration than that of the conventional elastic multifilament yarn materials, but when the elastic monofilament yarns are used for the production of a woven or knitted fabric, the resultant product has an undesirably high stiffness and hard touch, and when sewed by a sewing machine, the elastic monofilament yarns are easily broken by a sewing needle, and thus ground yarns, in which the elastic monofilament yarns are contained as an element, are frequently broken. Therefore, in practice, the utilization of the conventional elastic monofilament yarn is limited.